Abstract Detail

Zostera marina, a ubiquitous temperate seagrass, globally is found in Atlantic, Pacific, and Indian Oceans plus temperate seas. Preventing the crisis of 7% yr-1 global losses presently occurring needs solutions. Accurate remote sensing spectral signatures to capture seagrass extent would assist natural resource managers globally define and thus find solutions to sustain the remaining 171,000 km2 seagrasses. Despite endorsed international conservation policies, the losses of seagrasses’ vital services (fisheries nurseries, sediment stability, and carbon sequestration) is severe. Physiologically, the two fundamental bases of our light measurements are:1.) Einstein states light consists of particles, he called photons;2.) Feynman found “light is not really affected by surfaces”. In a plant, when a photon is incident on a leaf, it interacts with electrons throughout the leaf. The photon is scattered and a new photon emitted; an electron absorbs a photon and emits another photon. Consequently the “reflected” light receives the signature of the absorbing elements of the leaf (the pigments). If light merely struck the leaf surface to bounce off, it would not show the characteristic reflectance spectra. These reflectance spectra have a fundamental identity, with the quality and quantity of a species’ leaf pigments depending on the physiological state of the whole plant. Various species differ in leaf pigments types and quanitites, thus reflectance spectra is used to characterize plant communities and species physiology. We demonstrate for the first time the whole pigment array throughout visible range (400-1100nm) by spectrophotometer measurements reported for in vivoZostera marina whole plants’ responses challenged by diminishing intensities of four light colors. Lower values of Chlorophyll a resulted for blue and green diminished light (23% and below normal) while accessory pigments’ (435 to 580nm) partial absorption responses were enhanced and were statistically greater than those in red light.These results scale up to remote sensing marine measurements of seagrass signatures. The question of the physiological changes allowing only this higher plants group to evolve into the marine realm includes constraints of blue/green light. Results show an evolved, photosynthetically dynamic system allowing rapid adaptation of seagrasses’ to highly fluctuating marine/estuarine daily benthic spectral regime. Responses to diminished blue or green light involve accessory pigment responses. Indices of Chlorophyll a show significant color response differences versus the accessory pigments, perhaps an adaptation for preserving Chlorophylls.